Submission #1249143

#	Time	Username	Problem	Language	Result	Execution time	Memory
1249143		papaulo	Tracks in the Snow (BOI13_tracks)	C++20	2.19 / 100	166 ms	79088 KiB

tracks

#include <bits/stdc++.h>
using namespace std;

const int dy[4]={0, 1, 0, -1};
const int dx[4]={1, 0, -1, 0};

int main() {
    cin.tie(nullptr);
    ios::sync_with_stdio(false);
    int h, w;
    cin >> h >> w;
    vector<vector<char>> mat(h+2, vector<char>(w+2, '.'));
    vector<vector<int>> breadth(h+2, vector<int>(w+2, 0));
    for(int i=1;i<=h;i++) for(int j=1;j<=w;j++) cin >> mat[i][j];
    breadth[1][1]=1;
    vector<pair<int, int>> perb[2];
    perb[0].push_back({1, 1});
    for(int cur=0;!perb[cur].size(); cur^=1) {
        for(int i=0;i<perb[cur].size();i++) {
            auto pr=perb[cur][i];
            int y=pr.first, x=pr.second;
            for(int k=0;k<4;k++) {
                int newy=y+dy[k];
                int newx=x+dx[k];
                if(!breadth[newy][newx]&&mat[newy][newx]==mat[y][x]) {
                    breadth[newy][newx]=breadth[y][x];
                    perb[cur].push_back({newy, newx});
                }
            }
        }
        for(auto pr : perb[cur]) {
            int y=pr.first, x=pr.second;
            for(int k=0;k<4;k++) {
                int newy=y+dy[k];
                int newx=x+dx[k];
                if(!breadth[newy][newx]&&mat[newy][newx]!='.') {
                    breadth[newy][newx]=breadth[y][x]+1;
                    perb[cur^1].push_back({newy, newx});
                }
            }
        }
        perb[cur].clear();
    }
    int ans=0;
    for(int i=1;i<=h;i++) for(int j=1;j<=w;j++) ans=max(ans, breadth[i][j]);
    cout << ans << endl;
}

• Subtask 1: 0 / 30
• Subtask 2: 2.1875 / 70